GAGG:ce single crystalline films: New perspective scintillators for electron detection in SEM

Physica Status Solidi (a)

2019

The cathodoluminescence (CL) characterizations of Lu3Al5O12:Ce,Mg (LuAG:Ce,Mg) and of multicomponent (Lu0.25Gd0.74)3(Ga2.48Al2.52)O12:Ce,Mg (LuGAGG:Ce,Mg) single‐crystalline garnet films are supported by the optical absorption spectroscopy. Using this approach, the influence of the Mg‐to‐Ce concentration ratio on the CL spectra and the CL decay is analyzed. The crucial role of stable Ce4+ centers in CL is shown in Mg‐rich film studies. Although the CL intensity is somewhat reduced, drastic improvements in timing performance are demonstrated, including the CL decay time as low as 4.2 ns and the afterglow as low as 0.015% at 500 ns after the e‐beam excitation cutoff. These results predetermine the utilization of the LuAG:Ce,Mg and LuGAGG:Ce,Mg single‐crystalline films in e‐beam detection systems, where especially fast scintillator response is crucial.

Section: Resultssupporting

confidence: 68%

“…This effect was observed in GAGG:Ce films in our previous study. [19] The ionization of the Ce 3þ excited state should not depend on the Mg 2þ concentration, but can still contribute to the CL intensity decrease of all studied LuGAGG:Ce,Mg films, compared to the relative CL intensity of the 1LM1 with the 1LGM3 (Mg-free specimens) in Table 1.…”

Section: Resultsmentioning

confidence: 91%

Influence of Mg‐to‐Ce Concentration Ratio on Cathodoluminescence in LuAG and LuGAGG Single‐Crystalline Films

Lalinský

Schauer

Physica Status Solidi (a)

2019

“…In these garnet films, the mentioned influence of shallow traps and the ionization‐induced quenching of the Ce 3+ excited state is suppressed, which has a positive influence on the decay characteristics, including the substantial reduction of the afterglow. The GAGG:Ce (Gd 3 Al 5–x Ga x O 12 :Ce) single crystalline epitaxial films have also been studied as prospective scintillators in S(T)EM (Bok et al, ). Recently, the CL properties of the Mg 2+ co‐doped LuGAGG:Ce multicomponent single crystalline epitaxial garnet films were studied using a 10 keV collimated e‐beam (Schauer, Lalinsky, Kucera, Lucenicova, & Hanus, ).…”

Section: Introductionmentioning

confidence: 99%

Prospective scintillation electron detectors for S(T)EM based on garnet film scintillators

Schauer

Lalinský

Microscopy Res & Technique

2018

Self Cite

The performance of a scintillation electron detector for a scanning electron microscope and/or a scanning transmission electron microscope (S(T)EM) based on new epitaxial garnet film scintillators was explored. The LuGAGG:Ce and LuGAGG:Ce,Mg film scintillators with chemical formula (Ce0.01Lu0.27Gd0.74)3–wMgw(Ga2.48Al2.46)O12 were prepared and their cathodoluminescence (CL) and optical properties were studied and compared with the properties of current standard bulk single crystal YAG:Ce and YAP:Ce scintillators. More specifically, CL decay characteristics, CL emission spectra, CL intensities, optical absorption coefficients, and the refractive indices of the mentioned scintillators were measured. Furthermore, electron interaction volumes with absorbed energy distributions, photomultiplier (PMT) photocathode matchings, modulation transfer functions (MTF), and the photon transport efficiencies of scintillation detectors with the mentioned scintillators were calculated. A CL decay time for the LuGAGG:Ce,Mg film scintillator as low as 28 ns with an afterglow of only 0.02% at 1 μs after the e‐beam excitation was observed. As determined from calculated MTFs, the scintillation detectors with the new film scintillators lose contrast transfer ability above 0.6 lp/pixel, while the currently commonly used YAG:Ce single crystal scintillators already do so above 0.1 lp/pixel. It was also calculated that the new studied film scintillators have an 8% higher photon transfer efficiency, even for a simple disk shape compared with the standard bulk single crystal YAG:Ce scintillator. The studied LuGAGG:Ce,Mg epitaxial garnet film scintillators were evaluated as prospective fast scintillators for electron detectors, not only in S(T)EM but also in other e‐beam devices.

“…Successful result, light yield of 8700 ph MeV −1 under α‐particle excitation, i.e., 93% of reference bulk crystal light yield (reference crystal light yield: 53 800 ph MeV −1 under γ‐ray excitation) and suppressed slow scintillation component, was made possible only by the application of a novel BaO–B 2 O 3 –BaF 2 flux (BaO flux) . Bright luminescence response was already successfully exploited in scanning electron microscopy …”

Section: Introductionmentioning

confidence: 99%

Garnet Scintillators of Superior Timing Characteristics: Material, Engineering by Liquid Phase Epitaxy

Průša

Advanced Optical Materials

Babin

et al. 2017

Self Cite

Using liquid phase epitaxy, the Mg co-doped multicomponent garnet film scintillators of composition (Ce 0.01 Lu 0.27 Gd 0.74 ) 3-x Mg x (Ga 2.48 Al 2.46 )O 12 , x = 0-0.002 (0-700 at. ppm) are prepared. Following luminescence and scintillation characteristics and their dependence on Mg concentration are studied: photoluminescence emission and excitation spectra, radioluminescence spectra, photoluminescence and scintillation decay curves, light yield, energy resolution, and afterglow. At lower Mg concentration, the timing characteristics are slightly improved, while light yield and energy resolution are not negatively influenced. At higher Mg concentration, scintillation decay is significantly accelerated, although light yield is somewhat reduced. Afterglow values become extraordinarily low for a garnet scintillator, at least two times better than the best values published so far, which paves the way for their application in fast frame imaging applications. A mechanism of the improvement is shortly discussed.